Just for general typing, I have found Multikey very helpful. It has everything the user could want for a polytonic unicode Greek font, and lots of other stuff besides. Some of the keyboard assignments are a bit idiosyncratic, but hey, what's not? I can only speak to the Greek at this point – I've never really used any of the other fonts, including the Hebrew.

I've found this service to be brilliant (though slow on more than a few thousand characters). It follows normal betacode characters. More importantly, since I don't use Windows or Apple, it is nicely platform-independent.